What causes my vauxhall vectra to judder?

What causes rough idle on vauxhall 1600 vectra?

• Answer:

  Rough idle is often a result of poor air flow regulation and is most likely an electrical sensor problem. I'm assuming it drives well with this problem aside? The first part you should look at is the MAP (Manifold Absolute Pressure) sensor located on the inlet manifold as this can be directly responsible. If you have a trip computer you will notice increased fuel consumption as a result of the ECU trying to compensate, as if under a heavy load such as high power consumption or air conditioning. Other possible causes are the Air Mass Flow sensor located on the air intake system or Lamda sensor (Oxygen Sensor) located on the exhaust system. Although these parts are often associated with poor or weak running in general (check spark plugs for signs of weak or rich mix). I would also suggested having a look at your EGR valve (Exhaust Gas Recirculation). If this was stuck in the open possition, air and fuel mix will be displaced inside the combustion chamber. This can also cause your rough idle. If you have an engine management light while running then this means a drivetrain error number has been saved in the ECU and may aid in your fault diagnosis if you have the hardware to read it.